The clinical syndrome of multiple personality disorder (MPD) is poorly characterized although the total number of identified cases has increased by over 2000% in the last five years compared to the 200 years prior. In an attempt to better delineate the clinical phenomenology of MPD, cases meeting DSM-III criteria are collected on a standardized questionnaire (The NIMH Clinician's Questionnaire on Multiple Personality). This study has documented the existence of a clinical syndrome characterized by a core of depressive and dissociative symptoms and a childhood history of significant trauma, primarily child abuse.